Discovery and Characterization of Three New Escherichia coli Septal Ring Proteins That Contain a SPOR Domain: DamX, DedD, and RlpA
Discovery and Characterization of Three New Escherichia coli Septal Ring Proteins That Contain a SPOR Domain: DamX, DedD, and RlpA
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DOI：
10.1128/jb.01244-09
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发表时间：
2010-01-01
影响因子：
3.2
通讯作者：
Weiss, David S.
中科院分区：
文献类型：
--
作者：
Arends, S. J. Ryan;Williams, Kyle;Weiss, David S.
SPOR结构域长度约为70个氨基酸，存在于细菌基因组测序鉴定的bb101500个蛋白质中。来自大肠杆菌和新月形杆菌的FtsN细胞分裂蛋白的SPOR结构域已被证明与肽聚糖结合。除了FtsN外，大肠杆菌还有另外三种SPOR结构域蛋白——damx、DedD和RlpA。我们在这里展示了这三种蛋白都定位在大肠杆菌的间隔环上。DamX或DedD单独缺失或与编码其他分裂蛋白的基因突变联合缺失导致多种分裂表型，表明DamX和DedD参与细胞质分裂。相反，RlpA突变体分裂正常。后续研究表明，SPOR结构域自身在体内定位于室间隔环，并在体外结合肽聚糖。甚至来自异源生物（包括水蛭）的SPOR结构域在大肠杆菌中产生时也定位于间隔环，并与纯化的大肠杆菌肽聚糖糖块结合。我们推测SPOR结构域通过优先结合间隔肽聚糖定位于分裂位点。我们进一步认为SPOR结构域蛋白是细菌分裂装置的一个共同特征。在细菌双杂交实验中，DamX进一步被表征并发现与多个分裂蛋白相互作用。其中一个相互作用伙伴是FtsQ，一些合成表型表明DamX是FtsQ功能的负调节因子。
SPOR domains are similar to 70 amino acids long and occur in >1,500 proteins identified by sequencing of bacterial genomes. The SPOR domains in the FtsN cell division proteins from Escherichia coli and Caulobacter crescentus have been shown to bind peptidoglycan. Besides FtsN, E. coli has three additional SPOR domain proteins-DamX, DedD, and RlpA. We show here that all three of these proteins localize to the septal ring in E. coli. The loss of DamX or DedD either alone or in combination with mutations in genes encoding other division proteins resulted in a variety of division phenotypes, demonstrating that DamX and DedD participate in cytokinesis. In contrast, RlpA mutants divided normally. Follow-up studies revealed that the SPOR domains themselves localize to the septal ring in vivo and bind peptidoglycan in vitro. Even SPOR domains from heterologous organisms, including Aquifex aeolicus, localized to septal rings when produced in E. coli and bound to purified E. coli peptidoglycan sacculi. We speculate that SPOR domains localize to the division site by binding preferentially to septal peptidoglycan. We further suggest that SPOR domain proteins are a common feature of the division apparatus in bacteria. DamX was characterized further and found to interact with multiple division proteins in a bacterial two-hybrid assay. One interaction partner is FtsQ, and several synthetic phenotypes suggest that DamX is a negative regulator of FtsQ function.